Cardiopulmonary Injury in the Syrian Hamster Model of COVID-19

The Syrian hamster has proved useful in the evaluation of therapeutics and vaccines for severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2). To advance the model for preclinical studies, we conducted serial sacrifice of lungs, large pulmonary vessels, and hearts from male and female Syrian hamsters for days 1–4, and 8 post-infection (dpi) following infection with a high dose of SARS-CoV-2. Evaluation of microscopic lung histopathology scores suggests 4 and 8 dpi as prime indicators in the evaluation of moderate pathology with bronchial hyperplasia, alveolar involvement and bronchiolization being key assessments of lung disease and recovery, respectively. In addition, neutrophil levels, red blood cell count and hematocrit showed significant increases during early infection. We present histological evidence of severe damage to the pulmonary vasculature with extensive leukocyte transmigration and the loss of endothelial cells and tunica media. Our evidence of endothelial and inflammatory cell death in the pulmonary vessels suggests endothelialitis secondary to SARS-CoV-2 epithelial cell infection as a possible determinant of the pathological findings along with the host inflammatory response. Lastly, pathological examination of the heart revealed evidence for intracardiac platelet/fibrin aggregates in male and female hamsters on 8 dpi, which might be indicative of a hypercoagulative state in these animals.

Targeting ticagrelor: a novel therapy for emergency reversal

Newer P2Y12 inhibitors are prescribed in place of clopidogrel for patients with acute coronary syndrome (ACS) and are associated with significant bleeding risks. Currently, limited options exist for the management of life-threatening bleeding or acute reversal for patients on P2Y12 inhibitor therapy, specifically ticagrelor. Various interventions, including platelet transfusion and desmopressin, have been studied for ticagrelor reversal demonstrating limited success. PB2452 is a novel monoclonal antibody which binds to both ticagrelor and its active metabolite resulting in a rapid return of platelet aggregation. PB2452 has been studied in animal models and, most recently, in a Phase I trial in healthy volunteers. In animal models, PB2452 displayed rapid reversal of ticagrelor and its metabolites and return to near normal levels of platelet aggregation within 60 min. In healthy human volunteers, cohorts that received higher dose bolus and infusions of PB2452 over 12-16 h resulted in maximal and sustained reversal of ticagrelor inhibition of platelet aggregation. While it is currently not US Food and Drug Administration approved, future Phase 2 and 3 studies are currently underway that may lead to new directions for patients on ticagrelor therapy who require urgent reversal.

Circulating platelet aggregates damage endothelial cells in culture

BACKGROUND

Presence of circulating endothelial cells (CECs) in systemic circulation may be an indicator of endothelial damage and/or denudation, and the body's response to repair and revascularization. Thus, we hypothesized that aggregated platelets (AgPlts) can disrupt/denude the endothelium and contribute to the presence of CEC and EC-derived particles (ECDP).

METHODS

Endothelial cells were grown in glass tubes and tagged with/without 0.5 μm fluorescent beads. These glass tubes were connected to a mini-pump variable-flow system to study the effect of circulating AgPlts on the endothelium. ECs in glass tube were exposed to medium alone, nonaggregated platelets (NAgPlts), AgPlts, and 90 micron polystyrene beads at a flow rate of 20 mL/min for various intervals. Collected effluents were cultured for 72 h to analyze the growth potential of dislodged but intact ECs. Endothelial damage was assessed by real time polymerase chain reaction (RT-PCR) for inflammatory genes and Western blot analysis for von Willebrand factor.

RESULTS AND CONCLUSION

No ECs and ECDP were observed in effluents collected after injecting medium alone and NAgPlts, whereas AgPlts and Polybeads drastically dislodged ECs, releasing ECs and ECDP in effluents as the time increased. Effluents collected when endothelial cell damage was seen showed increased presence of von Willebrand factor as compared to control effluents. Furthermore, we analyzed the presence of ECs and ECDPs in heart failure subjects, as well as animal plasma samples. Our study demonstrates that circulating AgPlts denude the endothelium and release ECs and ECDP. Direct mechanical disruption and shear stress caused by circulating AgPlts could be the underlying mechanism of the observed endothelium damage.

Surgical considerations for the explantation of the Parachute left ventricular partitioning device and the implantation of the HeartMate II left ventricular assist device

Chronic heart failure is the leading cause of death in the world. With newer therapies, the burden of this disease has decreased; however, a significant number of patients remain refractive to existing therapies. Myocardial infarction often leads to ventricular remodeling and eventually contributes to heart failure. The Parachute™ (Cardiokinetix, Menlo Park, CA) is the first device designed for percutaneous ventricular restoration therapy, which reduces left ventricular volume and minimizes the risk of open surgical procedures. For the first time, we report a case of explantation of the Parachute ventricular partitioning device and transition to a HeartMate II™ left ventricular assist device and the surgical considerations for a successful outcome.

Successful heart transplantation using a donor heart afflicted by takotsubo cardiomyopathy

Takotsubo cardiomyopathy, also known as apical ballooning syndrome, stress cardiomyopathy, or broken heart syndrome, is a disease characterized by transient ventricular dysfunction in the absence of obstructive coronary artery disease. Herein, we present a case in which a heart with mild takotsubo cardiomyopathy was utilized as the donor organ for an orthotopic heart transplant.

Elevated transaortic valvular gradients after combined aortic valve and mitral valve replacement: an intraoperative dilemma

High transaortic valvular gradients, after combined aortic valve and mitral valve replacement, require prompt intraoperative diagnosis and appropriate management. The presence of high transaortic valvular gradients after cardiopulmonary bypass, in this setting, can be secondary to the following conditions: prosthesis dysfunction, left ventricular outflow tract obstruction, supravalvular obstruction, prosthesis-patient mismatch, hyperkinetic left ventricle from administration of inotropes, left ventricular intracavitary gradients, pressure recovery phenomenon, and increased transvalvular blood flow resulting from hyperdynamic circulation or anemia. Transesophageal echocardiography is an extremely useful tool for timely diagnosis and treatment of this complication. We describe a case of a critically ill patient with endocarditis and acute lung injury, who presented for combined aortic valve and mitral valve replacement. Transesophageal echocardiographic assessment, post-cardiopulmonary bypass, revealed high transaortic valvular gradients due to encroachment of the mitral prosthesis strut on the left ventricular outflow tract, which was compounded by a small, hypertrophied, and hyperkinetic left ventricle. Discontinuation of inotropic support, administration of fluids, phenylephrine, and esmolol led to resolution of the high gradients and prevented further surgery.

Impact of induction immunosuppression on survival in heart transplant recipients: a contemporary analysis of agents

INTRODUCTION

The impact of induction immunosuppression on long-term survival in heart transplant recipients is unclear. Over the past three decades, practices have varied as induction agents have changed and experiences grew. We sought to evaluate the effect of contemporary induction immunosuppression agents in heart transplant recipients with the primary endpoint of survival, utilizing national registry data.

METHODS

We queried the United Network for Organ Sharing (UNOS) data registry for all heart transplants from 1987 to 2012. We restricted our analysis to adult (≥18 yr) recipients performed from 2001-2011 (to allow for the potential for a minimum of 12 months post-transplant follow-up) who received either: no antibody based induction (NONE) or the contemporary agents (INDUCED) of either: basiliximab/daclizumab (IL-2Rab), alemtuzumab, or ATG/ALG/thymoglobulin. Kaplan-Meier estimates of the survival function as well as Cox proportional hazards models were utilized.

RESULTS

Of the 17 857 heart transplants that met the inclusion criteria, there were 4635 (26%) reported deaths during the follow-up period. There were 8216 (46%) patients who were INDUCED. Of the INDUCED agents, 55% were IL-2Rab, 4% alemtuzumab, and 40% ALG/ATG/thymoglobulin. Donor and recipient characteristics were evaluated. Overall, being INDUCED did not significantly affect survival in univariable (p = 0.522) and multivariable (p = 0.130) Cox models as well as a propensity score adjusted model (p = 0.733). Among those induced, ATG/ALG/thymoglobulin appeared to have superior survival as compared with IL-2Rab (log-rank p = 0.007, univariable hazard ratio [HR] = 0.886; 95% CI: 0.811-0.968; p = 0.522). However, in a multivariable Cox model that adjusted for recipient age, VAD, BMI, steroid use, CMV match, and ischemic time, the hazard ratio for ALG/ATG/thymoglobulin vs. IL-2Rab was no longer statistically significant (HR = 0.948; 95% CI: 0.850-1.058; p = 0.341).

CONCLUSION

In a contemporary analysis of heart transplant recipients, an overall analysis of induction agents does not appear to impact survival, as compared to no induction immunosuppression. While ALG/ATG/thymoglobulin appeared to have a beneficial effect on survival compared to IL-2Rab in the univariable model, this difference was no longer statistically significant once we adjusted for clinically relevant covariates.

Donor selection in heart transplantation

There is increased scrutiny on the quality in health care with particular emphasis on institutional heart transplant survival outcomes. An important aspect of successful transplantation is appropriate donor selection. We review the current guidelines as well as areas of controversy in the selection of appropriate hearts as donor organs to ensure optimal outcomes. This decision is paramount to the success of a transplant program as well as recipient survival and graft function post-transplant.

Dysregulation of PTEN in cardiopulmonary vascular remodeling induced by pulmonary hypertension

Pulmonary hypertension (PH) is a disorder of lung vasculature characterized by arterial narrowing. Phosphatase-and-tensin homolog on chromosome 10 (PTEN), associated in the progression of multiple cancers, is implicated in arterial remodeling. However, the involvement of PTEN in PH remains unclear. The objective of the present study was to determine the role of PTEN in pulmonary vascular remodeling using established models of PH. The study used rat models of PH, induced by monocrotaline (MCT) administration (60 mg/kg) or continuous hypoxic exposure (10% oxygen) for 3 weeks. Pulmonary artery smooth muscle cells (SMCs) were used for in vitro confirmation. Development of PH was verified by hemodynamic, morphological and histopathology analyses. PTEN and key downstream proteins in pulmonary and cardiac tissues were analyzed by western blotting and RT-PCR. PTEN was significantly decreased (MCT, 53%; Hypoxia, 40%), pAkt was significantly increased (MCT, 42%; Hypoxia, 55%) in tissues of rats with PH. Similar results were observed in SMCs exposed to hypoxia (1% oxygen) for 48 h. Ubiquitination assay showed that PTEN degradation occurs via proteasomal degradation pathway. Western blotting demonstrated a significant downregulation of cell-cycle regulatory proteins p53 and p27, and upregulation of cyclin-D1 in the lungs of both models. The results showed that PTEN-mediated modulation of PI3K pathway was independent of the focal adhesion kinase and fatty acid synthase. The study, for the first time, established that PTEN plays a key role in the progression of pulmonary hypertension. The findings may have potential for the treatment of pulmonary hypertension using PTEN as a target.

Endovascular abdominal aortic aneurysm repair in patients with ventricular assist devices

Long-term mechanical circulatory support devices are currently an established therapy for the management of end-stage heart failure, and current evidence supports their superiority in comparison to maximal medical therapy in these patients. Screening for peripheral arterial disease and abdominal aortic aneurysm (AAA) before left ventricular assist device (LVAD) implantation is recommended. Although repair of AAA before or during LVAD placement has been reported, management of patients with AAA after LVAD implantation needs to be further investigated. We describe our management and operative strategies in 2 patients on destination LVAD therapy who underwent successful endovascular AAA repair.

Outcomes of continuous flow ventricular assist devices

Heart transplantation is commonplace, the supply is limited. Many exciting changes in the field of mechanical circulatory support have occurred in the past few years, including the axial flow pump. Left ventricular assist device (LVAD) therapy is ever evolving. As the use of LVAD therapy increases it is important to understand the indications, surgical considerations and outcomes.

Type of Valvular Heart Disease Requiring Surgery in the 21st Century: Mortality and Length-of-Stay Related to Surgery

Aim:

While the incidence of rheumatic heart disease has declined dramatically over the last half-century, the number of valve surgeries has not changed. This study was undertaken to define the most common type of valvular heart disease requiring surgery today, and determine in-hospital surgical mortality and length-of-stay (LOS) for isolated aortic or mitral valve surgery in a United States tertiary-care hospital.

Methods:

Patients with valve surgery between January 2002 to June 2008 at The Ohio State University Medical Center were studied. Patients only with isolated aortic or mitral valve surgery were analyzed.

Results:

From 915 patients undergoing at least aortic or mitral valve surgery, the majority had concomitant cardiac proce-dures mostly coronary artery bypass grafting (CABG); only 340 patients had isolated aortic (n=204) or mitral (n=136) valve surgery. In-hospital surgical mortality for mitral regurgitation (n=119), aortic stenosis (n=151), aortic insufficiency (n=53) and mitral stenosis (n=17) was 2.5% (replacement 3.4%; repair 1.6%), 3.9%, 5.6% and 5.8%, respectively (p=NS). Median LOS for aortic insufficiency, aortic stenosis, mitral regurgitation, and mitral stenosis was 7, 8, 9 (replacement 11.5; repair 7) and 11 days, respectively (p<0.05 for group). In-hospital surgical mortality for single valve surgery plus CABG was 10.2% (p<0.005 compared to single valve surgery).

Conclusions:

Aortic stenosis and mitral regurgitation are the most common valvular lesions requiring surgery today. Surgery for isolated aortic or mitral valve disease has low in-hospital mortality with modest LOS. Concomitant CABG with valve surgery increases mortality substantially. Hospital analysis is needed to monitor quality and stimulate improvement among Institutions.

Outcomes in the current surgical era following operative repair of acute Type A aortic dissection in the elderly: a single-institutional experience

OBJECTIVES

We reviewed our single-centre experience with emergent operative repair of Stanford Type A aortic dissections, with particular attention to outcomes in the elderly.

METHODS

Consecutive adult patients undergoing emergent operative repair of acute Type A aortic dissections between February 2004 and December 2011 at a single institution were identified. Patients were stratified into elderly (≥ 70 years) and control cohorts (<70 years). Kaplan-Meier analysis was used to evaluate survival.

RESULTS

A total of 117 patients undergoing emergent repair of Type A aortic dissection were identified during the study period, including 31 (26.5%) elderly and 86 (73.5%) control patients. The mean age in the elderly cohort was 78.0 ± 4.7 years, with 41.9% (13 of 31) being 80 years or older. The elderly and control groups were well matched with regard to preoperative comorbidities (each P>0.05) and the presence of malperfusion at presentation (elderly: 19.4 vs controls: 27.9%, P = 0.35). The most common site of tear involved the proximal ascending aorta (elderly: 83.9 vs controls: 84.9%), with fewer cases affecting the aortic arch (12.9 vs 14.0%; P = 0.75). Operative data, including cardiopulmonary bypass and aortic cross-clamp time, concomitant aortic valve procedures and arch replacement were also similar between cohorts. Fewer elderly patients underwent hypothermic circulatory arrest (67.7 vs 90.7%, P = 0.002). Overall survival to discharge was 87.2% (n = 102), with no difference in the elderly (83.9%; n = 26) vs controls (88.4%; n = 76; P = 0.52). The 30-day (elderly: 82.8 vs controls: 86.2%), 90-day (elderly: 79.0 vs controls: 84.8%) and 1-year (elderly: 75.4 vs controls: 84.8%) survivals were also comparable.

CONCLUSIONS

Excellent operative outcomes can be achieved in elderly patients undergoing emergent repair of Type A aortic dissections. Advanced patient age should therefore not serve as an absolute contraindication to operative repair in this high-risk cohort.

Pulmonary hypertension secondary to left-heart failure involves peroxynitrite-induced downregulation of PTEN in the lung

Pulmonary hypertension (PH) that occurs after left-heart failure (LHF), classified as Group 2 PH, involves progressive pulmonary vascular remodeling induced by smooth muscle cell (SMC) proliferation. However, mechanisms involved in the activation of SMCs remain unknown. The objective of this study was to determine the involvement of peroxynitrite and phosphatase-and-tensin homolog on chromosome 10 (PTEN) in vascular SMC proliferation and remodeling in the LHF-induced PH (LHF-PH). LHF was induced by permanent ligation of left anterior descending coronary artery in rats for 4 weeks. MRI, ultrasound, and hemodynamic measurements were performed to confirm LHF and PH. Histopathology, Western blot, and real-time polymerase chain reaction analyses were used to identify key molecular signatures. Therapeutic intervention was demonstrated using an antiproliferative compound, HO-3867. LHF-PH was confirmed by significant elevation of pulmonary artery pressure (mean pulmonary artery pressure/mm Hg: 35.9±1.8 versus 14.8±2.0, control; P<0.001) and vascular remodeling. HO-3867 treatment decreased mean pulmonary artery pressure to 22.6±0.8 mm Hg (P<0.001). Substantially higher levels of peroxynitrite and significant loss of PTEN expression were observed in the lungs of LHF rats when compared with control. In vitro studies using human pulmonary artery SMCs implicated peroxynitrite-mediated downregulation of PTEN expression as a key mechanism of SMC proliferation. The results further established that HO-3867 attenuated LHF-PH by decreasing oxidative stress and increasing PTEN expression in the lung. In conclusion, peroxynitrite and peroxynitrite-mediated PTEN inactivation seem to be key mediators of lung microvascular remodeling associated with PH secondary to LHF.

Induction of early biomarkers in a thrombus-induced sheep model of ischemic heart failure

The levels of brain natriuretic peptide (BNP) and monocyte chemoattractant protein-1 (MCP-1) are known to be increased in the sera of subjects with heart failure. Existing models do not account for the biomass of thrombus that occurs in patients undergoing myocardial infarction. In this study, we compared the expressions of sheep-derived genes for BNP, MCP-1, and atrial natriuretic peptide in a new large-animal model of thrombus-induced heart failure. Thrombus of autologous platelets was injected directly into the left circumflex coronary arteries of sheep. Cardiac ischemic injury was evaluated by troponin I levels, and heart failure progression was monitored with the aid of echocardiogram-based evaluation. After outlined time intervals, the sheep were killed and their hearts excised for tissue sampling. Reverse transcription polymerase chain reaction, Western blot, and enzyme-linked immunosorbent assay (ELISA) tests were performed to establish gene and protein expressions. At 72 hours after embolization, myocardial BNP and MCP-1 expressions had increased significantly in the ischemic region, compared either with the nonischemic region or with tissue from healthy sheep. As heart failure progressed to 90 days after embolization, the expression of BNP in the ischemic region decreased, whereas its expression in the nonischemic region increased several fold. In contrast, MCP-1 gene expression showed no changes in either tissue after 90 days of embolization. Plasma levels of BNP, determined by Western blot and ELISA, also correlated with the gene-expression studies. Our results show regional changes in BNP and MCP-1, as well as differences in the expression of these 2 genes.

Shortness of breath: pulmonary embolism, ischemic heart failure, or both? The role of concomitant surgery

We present a case of a patient who underwent successful concomitant surgical management of his massive pulmonary embolism and severe multivessel coronary disease. His presentation with shortness of breath prompted a comprehensive evaluation, which revealed both problems. This experience emphasizes the importance of considering both problems, because treating one but not the other could be catastrophic.

Efficacy of chordal cutting in alleviating ischemic mitral regurgitation: insights from 3-dimensional echocardiography

Background

Ischemic mitral regurgitation often complicates severe ischemic heart disease and adversely affects the prognosis in these patients. There is wide variation in the clinical spectrum of ischemic mitral regurgitation due to varying location and chronicity of ischemia and anomalies in annular and ventricular remodeling. As a result, there is lack of consensus in treating these patients. Treatment has to be individualized for each patient. Most of the available surgical options do not consistently correct this condition in all the patients. Chordal cutting is one of the newer surgical approaches in which cutting a limited number of critically positioned basal chordae have found success by relieving the leaflet tethering and thereby improving the coaptation of leaflets. Three-dimensional echocardiography is a potentially valuable tool in identifying the specific pattern of tethering and thus the suitability of this procedure in a given clinical scenario.

Case Presentation

A 66-year-old man with cardiomyopathy and ischemic mitral regurgitation presented to us with the features of congestive heart failure. The three-dimensional echocardiography revealed severe mitral regurgitation associated with the tethering of the lateral (P1) and medial (P3) scallops of the posterior leaflet of the mitral valve due to secondary chordal attachments. The ejection fraction was only 15% with severe global systolic and diastolic dysfunction. Mitral regurgitation was successfully corrected with mitral annuloplasty and resection of the secondary chordae tethering the medial and lateral scallops of the posterior leaflet of the mitral valve.

Conclusion

Cutting the second order chordae along with mitral annuloplasty could be a novel method to remedy Ischemic mitral regurgitation by relieving the tethering of the valve leaflets. The preoperative three-dimensional echocardiography should be considered in all patients with Ischemic mitral regurgitation to assess the complex three-dimensional interactions between the mitral valve apparatus and the left ventricle. This aids in timely surgical planning.

Intestinal Ischemia Complicating Ascending Aortic Dissection: First Things First

Typically acute dissections of the ascending aorta are considered operative emergencies with delays in treatment potentially resulting in considerable morbidity and mortality. However, occasionally associated unstable or poorly defined problems (such as neurologic impairment or end-organ ischemia) may warrant further investigation and possible treatment to facilitate safe aortic repair. We present a case of acute ascending aortic dissection associated with an intra-abdominal vascular and enteric catastrophe that was successfully managed prior to aortic repair.

Technical Considerations for Myocardial Revascularization in Congenital Bilateral Hypoplasia of the Pericardium

Congenital hypoplasia of the pericardium is a rare clinical condition that is typically encountered as an incidental finding during routine thoracic imaging or cardiothoracic surgery. Chest pain symptoms, when they occur, are often initially attributed to coronary ischemic syndromes, but herniation of cardiac structures through the pericardial defect, ischemia from torsion of great vessels, or compression of pulmonary parenchyma through defects between the aortic and pulmonary arteries can occur. Careful attention to cannulation techniques, conduit length, and the aberrant course of the phrenic nerves, typically through pericardial fibrous bands, is critical to the successful conduct of cardiac surgery.